The alignment of the main asteroid belt with the orbital plane of the planets is a fundamental, well-known astronomical fact that requires no academic citation.
The claim states that the main asteroid belt lies in a plane closely aligning with the orbital plane of Jupiter and Earth (the invariable plane/ecliptic plane of the solar system). This is basic, textbook observational astronomy regarding solar system architecture. None of the retrieved papers specifically evaluate or test this basic geometric truism as a novel hypothesis, making it common knowledge.